Document Signing

requestSignature() asks the user's credential wallet to sign a document hash. The wallet shows a consent popup; the user approves or rejects. No private key ever leaves the wallet.

SignRequest

TypeScript

 interface SignRequest {
  hash: string            // Hex-encoded file hash
  fileName: string        // Original file name (displayed to user)
  hashAlgorithm: string   // 'SHA-256' | 'SHA-384' | 'SHA-512'
  fileSize: number        // File size in bytes
}

SignResponse

TypeScript

 interface SignResponse {
  approved: boolean       // Whether the user approved
  did: string             // Signer's DID
  signature: string       // Base64url-encoded signature
  publicKeyJwk: JsonWebKey // Public key for verification
  timestamp: string       // ISO 8601 timestamp
  storeToken: string      // Opaque token for anchoring
}

Nonce-based CustomEvent Pattern

Each signing request generates a unique nonce. The wallet extension listens for sign-request CustomEvents and responds on sign-response with the matching nonce. This prevents replay and cross-tab interference.

User Consent

💡

The wallet extension displays a popup showing the file name, hash algorithm, file size, and the requesting origin. The user must explicitly approve before any signature is produced. If the user rejects, approved is false and all other fields are undefined.

Full Example

TypeScript

 import { pickWallet, requestSignature } from '@attestto/id-wallet-adapter'

// 1. Hash the file
const file = document.querySelector('input[type=file]').files[0]
const buffer = await file.arrayBuffer()
const hashBuffer = await crypto.subtle.digest('SHA-256', buffer)
const hash = [...new Uint8Array(hashBuffer)]
  .map(b => b.toString(16).padStart(2, '0'))
  .join('')

// 2. Pick a wallet
const wallet = await pickWallet({ render: 'modal' })

// 3. Request signature
const response = await requestSignature(wallet, {
  hash,
  fileName: file.name,
  hashAlgorithm: 'SHA-256',
  fileSize: file.size,
})

// 4. Verify the response
if (response.approved) {
  console.log('Signed by:', response.did)
  console.log('Signature:', response.signature)
}